Transformer



AfNfsMlTH Re. 19,957 l TRANSFORMER May 5, 1936.

original Filed nec. 27, 19:53 'hzhsheets-sheet 2 Z/ A:inventor ttotneg Reissued May 5, 1936 l TRANSFORMER Anthony N. Smith, Girard, Pa., assigner, by

mesne assignments, Vto The Girard Manufacturing Company, Girard, Pa., a. corporation of' Pennsylvania 'i Original No. 2,019,196, dated October 29, 1935,

Serial No. 704,178, December 27,

reissue November 30, 1935', Serial No.

cation for 52;'126

This invention relates to electrical apparatus, particularly to variable voltage step-down transformers for operating electrical toys, especially toy railroads, from a household power line.

24 Claims... (ci. r11- 119) 1933. Applicoil I3 having the usual primary and secondary lwindings I4 and I5 respectively. As shown in thedrawings the secondary Winding is composed of two layers of suitable wire, being separated 5 The present disclosure deals with an embodifrom eachother by the insulation I6, The layers 5 ment wherein the apparatus is designed to perare closely Wound, the adjacent wires prefermit manual regulation,and control of current ably being in side by side contact, as shown, thereim between-an 1x1-put and out-put: when using insulated Wire. The secondary wind- An object of this inventionis the provision in ing encompasses the primary/and is insulated an apparatus of such character, of a novel slidtherefrom as indicated at I] or infanylwell known lo ing contact with the control and the mounting i manner. The arrangement of the secondary therefor, to the end of obtaininga smooth'cony Winding intO two layers Permits Of the Outside tinuous gradual variation of voltage, a convenient layer carrying Only one half 'of the total voltage, zero voltage or open circuit position, and'a com- 0r in' other words, one half maximum to minipletely concealed and'protected sliding contact milm- It iS t0 be undelSfOOd; however. that the 15 system devqid of specal spaced taps or Contact coil may be so constructed that the entire range elements with their added cost and .their at? from minimum to maximum 'may be had by the tendant. operating difficulty by reason of open Se 0f 011e layer.

circuiting taking place between successive con- The Coil 'i3 iS rigidly Secured Within ein Opentact elements, ing I8 formed by laminated core sections I9 20 Another object is the provision, in such m3,. thus forming a unitary structure or coil unit. paraitus, of a self-contained coil mount and ,a T0 Secure andlpl'eperiy position this unit Withinsliding f contact member adapted for support the housing, I have provided a frame 20 '0f Subwithin a separable Section casing stantially U-shaped-constructlon. The coil unit,

A fui-ther object is' the provision, in. Such apwhich embraces the laminated sections and coil 25 vparams, of a separable'- casing having sliding per se. is held .within the frame and restrained Contact agtuator means .Supported therein in against movement therein by means of the side slidably straddled engagement with a casing Wall. flanges. 2 and the 012 Portion 22. The top D0I` Other objects will beA apparent fromthe descrip- F1011 iS IJIOVided- With tfmgues 23 f0.1' engagement tion. The'present disclosure constitutes an ex# With the Sides 25 through Slots 25 'formed there- 3G position of-the invention .as reduced to practice. in- These tongues are twisted as distinguished It is to be understood that the structural defrom being bent at right angles'in Order to pro- .ta-ils thereof may be varied to any extent not ject laterally and serve t0 SPM? the frame and inconsistent with the scope of the inventionv as -coillom the hflusing. 8S Clearly Shown in Figures i5 claimed, 'Y 2 and 4; 35

In the drawings: vDepending legs 26, formed from the bottom Figure 1 15 an assembled'perspectiveview of a' portion of ,the-frame, are secured to and rest structure made in accordance with the invention.. upon the base I2 in a manner to space theframe l t Figure 24s an internaifelevation with a section therefrom Tongues 21, integral with the lees i0 of the separable casing removed. 26 .pass through slots 28 in the base for securely 49 Figure 3 is a section taken on the line M of t hQldng the flime ihelet- The tongues. 'as a Figure z I matter of course, being bent at right angles to Figure 4 is a dis-assembled perspective .view of` Perform 'this function' the various parts of the structure' illustrated. Plvot lbearings 29 inthe form of depending 5 v The embodiment, shown in Fm' e 1 cmnprise` nangesare formed from the bottom portion of 45 a. transformer lIll that is particularly adapted the frame afnd are Provided-With openings 3 lor use in connection with the operation of ty therein for the receptlm of a' plVotPin or #haft trains and other electrically operated toys. Its i The shaft 3| has mounted thereon a composite- 40 detauS'mmpr-ise'a coverisection u that is 'sepa' switch device which comprises an actuator.' such 50 rably connected byV sliding inter-tting engagement with a basel section I'Z, both sections being constructed preferably of steel or other suitable material. y 5 Secured within the housingisvatransformer as a. ilnger piece 33, a contact element and an insulating strip or means 35. 'I'he tlnger piece,

as illustrated, is composedof anat strip ol' metal, although insulating lmaterial could'be used-'hav'- ing a lower portion 36 formed at right angles 55 thereon', the end 31 thereof being turned upward and provided with a shaft opening 33. A. similar opening 33 is also formed in the linger piece 33.V vThe lower portion 330i the finger piece is provided with slotted openings 40 for the reception of the bifurcated end 4I of the insulating strip 35, which construction securely holds the strip to the nger. piece for movement therewith.

, A suitable pivot opening 42 4is provided in the insulating strip 35 for the reception of the shaft 3| 1 'I'he contact element 34 -comprises a bowed strip of resilient metal, slotted as at 43 to form thereon a tongue 44. A depressed or indented nub 46 is positioned on the end of the contact element to actively form electrical'c'ontact between the contact` element and the outer secondary winding of the coil as will be hereinafter set forth, the insulation of the wire, when linsulated, being reinoved on the outer face oi'` the coil.' The rectangular section of the ore gives -the coil a iiat face of substantial ar a on which I the arcuate movement of the con ct `nub 4 6 is the insulating strip 35 is a terminal connecter 41,"4

received. The mechanical moveme and the voltage variation is gradual.

Interposed between the contact elem nt 34 and which is' held therebetween by means of a rivet 43 which passes through openings 43 and 50 in the contact element and strip respectively. A

projecting portion 5I on the tongue `4 4 lits within a slot 32 in the strip 35 and prevents relative.v

movement between the strip and contact element.

At one side of the convolutions of the coil and iiush therewith .is mounted a flat strip of insulating ymaterial to .form 'and function as a cir- -cuit cut-oir 5 2. A suitable mounting secured PTOP- to one of the laminated sections serves erly position the cut-oir, the mount being provided .with tongues 53, to rigidly hold the strip The bottom section or bas I2 carriesthe-'end walls 55 oi.' the housing structure and these walls are provided with tongues 56 formed on the upper ends thereof, these tongues being so arranged as `to be receivable through the slots 51 formed in the cover Il. -'Iheend walls -of the. frame 20 are'also'provided with tongues 53 receivable' through s1o'ts53 in the cover. When the housing sections are. assembled, .the tongues 53 -and-5i! project throughthe slots- 51 and Bil-respectively and are bent atright angles-ln a manner to se 'Ihe base l2 ds so `form'ed, -.as -to yprovide a pairv ofl uptumed angesmembers G0. whichproperly posi" tion the cover Il when assembled. Sim-i131' 'mange members 5I 'are -formed ,en the ends oi."y R the cover and serve to prevent any spreadg'ot trouser the cover limite .the end walls of the baseor bottom' section- VA downwardly extending cup shaped portionv 152- is formed' on the bottom of the base in a. flanges! in a manner to permit of theiree movement or the switch device, the cover. being Vprovided witha depressed portionj63 adjacentthe cup shaped portion on theiiange G0 to 'coop- `crate with the same for the free movementof t .the'switch device. Suitable sto -54 formed ons.

.theinger piece 33.l A It will bejnoted-that the -4fronti'a'ce of the vcom ercarrie'sza rib orjgu'ide 65 t projecting-inwardly .'in a mannerf'to 'spac'efthe insulating strip awaytromthefside ofjthe cover. This rib'tunctlons toiorcejthe insulating 'strip 'towards the coil, andas a. consequence-.ot

this' action, the contact elementiwhich issecured,

is smooth Ato the bight 36 `in such manner that the: insulat-` l Il.:

to the strip, is tensioned against a portion of the secondary winding of the coil or the cut-oi! l2, asthecasemaybe.

The end walls of the base are provided with thelin-put cable 66a to the primary and the out.

put 4terminal posts. A suitable cable 68 connects terminal connector I4l to a secondary or output terminal B9 positioned in onelof the openings 61, the same being insulated from the end wall. Itcan be readilyunderstood from this etrangement of the parts, that the switchdeviceis infterposed in the secondary circuit and the voltage controlled therethrough byl movement of thev switch -device in relation to'thecoil.

Indicia l0 on the outside of the cover indicates to the operator the various positionsin which to" place the ringer piece in Qrdefto-obtain any de- -.sired voltage within the range provided .by the secondary windings on the. coil.

A It will be noted that the frame is held in spaced relation to the housing, and that the' top portion openings 65 and 51 which receive respectively 22 is provided with cut-away portions, in order that a free circulation of air may be obtained to. assist in cooling the coil unit.

In operation, the parts being assembled as shown-min Figuresl to'3 inclusive, the movement of the ringer piece and associated parts .towards the cut-'off 52 will reduce the amount of voltage imparted through the secondary circuit as asmall number of convolutionsl of wire on-the secondary winding of 'the coil are in the circuit.

It also follows that movement o1' the finger piece 'in the opposite direction will increase the amount g of voltage as more convolutions are inthe circuit. Continued movement of the iinger piece circuit. l Cable 68 connects one side of the secondary e011 the secondary coil is connected through wire?" with a terminal `post, not shown, mounted on'a Wall of the base l2 adjacent theQterminal post 59.- The insulating strip 35 provides a mountingfor` the spring tensioned contact finger 34 and ,serves to maintainv the contact-iinger outof any towards thecut-oft 52jwill position the contact 'element on the insulating strip and break the k 4d with the terminal post 69 and the othery side of electrical contact with any portion of the cli-S1115A f structure. This insulating strip 35 is attached ing strip is moved by and in conjunction withtlie actuator ann or linger 33. Both actuator -vnnger 33 andthe -insulating strip 3.", are pivoted on the .pintle 3| for free movement with res'pect'theret. The edge of the casing sectionll .is suitably SIOttedadjacent'the depressed portion'6'3 to ac? commodate'the'l` dispositionof thepintle 3|. z

' Ajfeature' oivthe invention resides i-n the i'act that theactuator arm 33 and the in sulatorstr'ip 35 straidlethe adjacent edge or thecasing cover. o section I I in slidable relation tothe opposed facesA thereof.- 'Thacover section I I ,is applied and dis-' engaged by sliding between the actuator linger 43 3 and the insulator strip. This` insures a positive disposition of the lactuator ilnger on the exterior ofthe, casing.l .It will beapparent that in this as sembly'the 'actuator and the contactiinger aref.'

In 'a current device having a pivotally mounted upon; the coil carrying frame these elements vdo nothave any-connection eitherelectrical or mechanical withfeither of the 70 separable casingfs'ectins. In this construction no v"part ofthe secondary, circuit-passes th'.y ugh the .t '.'actuator nger 33 or its pintle 3l.' n t l IWI claimasmy invention: f l

and a conductor coil in said mount; means for" establishing slidable contact with the conductor coil, means disposed externally of the closure-provided wall of thecasing for moving said contact establishing means over said conductor coil, means carried by said coil mount and providing a pivot for said contact establishing means and its moving means, and an operating connection between said contact establishing means and the moving means therefor at one side of the pivot, said moving means straddling the loweredge of said closure provided casing wall adjacent said base whereby to admit of ready removal of the casing without interference with said moving means.

2. In acurrent regulating device having a casing, a coil mount therein, and a conductor coil in said mount; #means for establish' /contact with the conductor coil, an linsulay r member supporting said contact means, m ans on said coil mount providing a pivot for member, an actuator memberv havin a portion pivotally connected to said pivot providing means, means supporting said actuator member on the coil mount, said actuator-straddling a lower edge portion of a wall of said casing and having a portion disposed externally of the 'casing Vand unsupported thereby, and said insulator member l having a fixed connection Awith said actuator member within the casing.

3.. In'aA current regulating device, a casing, a.

coiled. conductor therein, means supporting and anchoring'saidgconductor in the casing in spaced relation from the walls thereof and comprising outwardly extending tongues, a manuallyl operable contact member, means carried by said conductor supporting means and providing a pivot for said contact member, means externally of said casing for moving the contactmember on its pivot over the conductor coils and supported solely by said pivot providing means, and an operating connection vbetween said contact member and its moving means.

4. In a current regulating device having la casing and a conductorl coil supported therein; a ,pivot pintle, 'a strip of insulating material freely pivoted on said pintle, an actuator finger freely pivoted on said p lntle, means operatively connect-V in g said strip and iingernin ilxedrelation, a contact element carried by said strip and vspaced from said pintle in slidable engagement with said conductor coil, and said actuator finger and 4insulating strip straddling a wall of the' casing in slidable unsupported relation.

5. In a current regulating device, 'a separablesections casing, a coiled conductor therein, a takeoi contact member having sliding contact with the conductor c0115..' a support for said conductor, a pintle carried by said support and sections of said casing to' permit ready separation and assembly thereof, an 'insulatormember plvoted on said pintle, said contact member being carried by said insulating member, an actuator .for said .contact member pivotedon said pintlev and disposed over the exterior of the casing, and an operative connection@ between said actuator and insulator member internally of 4the casing.

6. In a transformer. structure,V a casing, a transformer' coil .'secured therein, a secondary lead .for said coil, ajswitch device secured to said casing and provided with' a contact element,a linger piece, insulating means securing Asaid consa? insulator.

cleanoi.' the tact element and said piece together, and an electrical connection between said contact element and said lead, said contact element being capable of engaging said coil in a manner to vary thevoltage of current passing through said lead.

'7. In a transformer structure, a separable.'

`housing, a transformer coil located therein a secondary lead for said coil, a switch device associated with said coil and operable without said housing, said device having a finger piece; a contact element, and insulating means securing said contact to said piece, a terminal connector interposedbetween said contact element and said means and connected to said lead, and said contact element engaging said coil 'in such manner that the voltage of current passing through said lead may be varied upon movement of said finger piece.

8. In a transformer structure, comprising a separable housing, a transformer coil within said housing, a secondary leadfor said coil, a frame f or holding said coil and spacing'thesame from said housing, said transformer having a linger piece, a Contactv element, and insulating means securing said contact to said piece, a terminal connector interposed between said contact element .and said means andconnected to said lead, and said lcontact element engaging said coil in such manner that the voltage of current passing ment of said finger piece.

9. In a transformer structure, a housing, a .transformer coil within said housing, a secondary lead for said coil, a frame for. holding said coil and spacing the same from said housing, a switch device associated with said coil and that the voltage of current ,passing through said l lead may be varied upon movement of said nger.

piece.

'. In a transformer structure, 4a. housing, 'a

transformer cil within said housing, a secondary lead-for s aid coil, a frame for holding said coil and spacing the same from said housing, a switch 7element contacting said' coil within said housing and operable without said housing, means connecting said element. and said lead, means insulating said element from said housing and normally urging-said element towards said-coil, and means controllable without said-housing through said lead may be varied upon move-4 operatable without said housing, means pivotally connecting said switch device to said frame, said for positioning said element relative to said coil in such manner that .thevgltage of. current passing through said lead may beyaried.

transformer 'coil having ari-exposed, secondary winding positioned within said housing, .a secondary lead for said coil, aecontact element engaging saidryvinding and connected to said lead,

roads, from a household power line, said trans- 11. Ina transformer structure, a housing, a? y he position of said element relaformer comprising an iron core having a straight 'core leg rectangular in` cross-section, a primary winding consisting of a number of vlayers of wire lwound about said core, a flexible -cord and plug joined thereto for connection to a power line, a secondary wirding including a layer of closely wound wire surrounding said straight core leg, said layer having relatively flat side faces paralleling the flat sides of the core leg, a contact .10 arm oscillatable 'about an axis disposed transversely of the core Vleg and offset sidewardly therefrom, the length and pivoting of the contact arm being so relatedto the secondary winding that-the end of the contact arm may be swept lentirely across the-winding in an arcuate path while riding 'on one of the relatively flat sidel faces of the winding, thereby.I varying the output voltage in a smooth continuous manner,

f a casing surrounding said transformer and said 20 contact arm, and a control handle outsidesaid casing connected casing,

13. A variable voltage step-down transformer for operatingelectrical toys, especially toy railroadsffrom a household power line, said transformer comprising -an'iron core leg which is rectangular in cross-section, a primary winding consisting of a number of la'yers `of wire wound about 'to the contact arm within the said core and adapted to be connected to'a flex- Aible cord' and vplug for connectionto a powen line, a secondary winding including a layer of closely wound wire surrounding winding, said layer having relatively iiat side faces paralleling 'theflat sides of the core leg,

35 a contact arm oscillatable about an axlsdisposed transversely of the'core leg and offset sidewardly therefrom, the length and pivoting .ofthe contact arm'being so related to the secondary windling that the end of the contactarm may be 40 swept entirely across the winding in an arcuate to a flexible cord and plug for connection to the power line, a secondary winding including nrst 'and second layers of closely wound wire, a movable contact arm, said contact arm being so related to the transformer winding that the-end of the contact arm may be swept entirely across the outer layer of secondary winding to vary the voltage in a smooth continuous manner from about half to maximum value, a pair of binding posts one of which is connected'to the starting end of the inner layer of secondary winding, and the other of which is 4connected tosaid-movable contact arm, and a control handle connected to the contact arm.4 i

16, A variable voltage 'step-down' transformer for operating electrical toys, especially toy railroads, from a' household power line, said transformer comprising an iron core, a primary windin'g consisting of a number of layers of wire wound about said core, a exible cord and plug joined thereto for connectionl to the power line, a secondarywinding including a layer of closely wound wire-about the `outside of the primary winding, a contact arm oscillatable about an axis disposed transversely of the axis of the -windings and offset sidewardlytherefrom, the length and pivoting of the contact arm being so related to the transformerwinding that the end of the contact arm may be swept across the winding in .order to vary the output vottage in a smooth concasing connected .to the contactarm vwithin the -path while riding on one of the relatively fiat side faces of the winding-thereby 'varying the'- output voltage in a smoothcontinuous manner,

= a casing-surrounding said transformer and said contact arm, means on said core for spacing the same from the walls of the casing, and acontrol handle outside of said casing connectedlto but insulated from the contactarm within the casingf 14. A variable voltage step-down- .transformer or operating electrical toyS. especially ty rail" roads,'f rom a; household powert line, said transformer lcomprising aniron core, a primary winding consisting" of a number oflayers o wire wound about said core, a flexible cord .and plug a, secondary' winding including4 a plurality of closely wound layers of wire connected in series or end to end, a movable contact arni ,'said con-" tinuous manner, a casing surrounding said trans-v former and said contact arm, means on said core.

for positioning the. same inspaced relation with respect tothe walls of the casing, a pair of bind-- ing posts or connections one o f which is connected to one end of the secondary winding and the other 'of which is connected to said movable' contactarm.. and a control handle outside said casing, said control handle being insulated from said` contact arm. i

`17. A variable voltage step-down transformer for operating electrical toys, especially toy railroads, froma householdpower line, said transformer comprising, an iron core, a primary wind'- 4 55 Joined thereto forjfconn-ection tothe power line,

ondary winding to varytheoutput voltage in a.

smooth fco'ntinuous manner between Aan intermediate and-'a maximum value, a'p'air ofbinding posts. one of which is connected to the inner end of the' secondary winding, andthe other' of 1which is connected to said 'movable' contact arm,

a controlhandle connectedto the contact 1 5- A-variable step-down'tranformer' for operating electrical toys, especially toy railroads; from' a householdpowe'r line; said transformer lcomprising an iron core. 'a primary winding consisting of a number oflayers" ofwir'e wound l'iti about -laid core and adapted to be connected ing consisting-of,` a number of ylayers of wire wound aboutsaid core and adapted to be oon-J4 lnected to a ilexiblecord andn plug for 'connection to a power line, a secondary winding including a layer of closelywound wire wound about-l the outside of the. primary winding, said layer being as long as' the primary winding. a movable contact arm, 4saidcontact arm beingl so related tothe transformer winding that the end of the contact arm may be swept entirely across Vthe o uterlayer of winding to varythe voltage in a smooth .continuous manner, a 'casing surrounding said transformer and said contact arm, means on said core -for positioning the sanieinl spaced relation'with respect toitheiwalls of the casin g.

a. pair of 'binding posts or connectionsj one of which .is connected to one end of the secondary winding-and thel other of which is connected to said movable contact arm.- a control handle outside said casing connected to thecontactlayer oirv within the casing, stop-means tolimit the lmove-*- 'm'ent in either direction of the control handle 4and contact arm, the' stop at one end permitting 'said' contact arm to movel beyond the transformer 'winding and means disposed at said enjd' of the transformer winding --iiooeceive4 and guide thel contact arm during its continued movement bevond the' transformer winding-said means being"` arranged' approximately' in 4 the plane ofthe outer 18. A variable voltage step-down transformer for operating electrical toys, especially toy railroads, from a household power line,v said transformer comprising an iron core, a' primary winding consisting of av number of layers of wire wound about said core, a secondary winding including a layer of closely wound wire, a contact arm oscillatable about an axis disposed transversely of the axis of the secondary Winding and oiset sidewardly therefrom, the length and pivoting of the contact arm being so related to the winding that the end of the contact arm may be swept entirely across the Winding in order to vary the output voltage in a smooth continuous manner, a casing surrounding said transformer and said contact arm, means on-said core for positioning the same in spaced relation with respect to the walls of the casing, a control handie outside said casing connected to the contact arm within the casing, stop means to limit the movement of the control handle and contact arm, the stop at one end permitting said con,

tact arm to move beyond the transformer wind# ing, and a slab of material disposed at said end of the transformer winding to receive and guide the contact arm during its continued movement beyond the transformer winding. f

19. A variable voltage step-down transformer for operating electrical toys, especially toy railroads,'from a househdld power line, said transformer comprising a laminated H type iron core including center and outside legs joined by transverse end legs, a primary winding consisting of a number of layers `oi wire wound about said center leg, a flexible cord and plug joined thereto for connection .to a power line, a secondary winding including allayer of closely wound wire about the outside of the primary Winding, a contact -arm oscillatable about an axis disposed transversely of the corelegs andoffset sidewardly. from the center leg toward an outside leg, the length and pivoting of the contact arm being so related to the transformer winding that the end of the con.- tact arm may be swept entirely across a side face of the winding in order to varythe output voltage in a smooth continuous-manner. f

20. A variable voltage step-down transformer for operating electrical toys, especially toy railroads, froma household power line, said transformer comprising a laminated H type .iron core l including center and-outside legs joined by transverse end legs, a primary winding consisting of a number of layers of wire wound about said center leg and adapted to be-connected to a nexible cordA and plug for connection to a power line, a secondary winding including a-layer of closely Wound wire about the outside-ofthe primary winding, a movable contactarm so arranged that the end thereof may be. swept entirely across the outermost layer of winding in order to vary the output voltage in a smooth continuous manner, a casing surrounding said transformerjand said contact arm, means on the exposed part'of said core for positioning the same in spaced relation with respect to the walls of the casing, a control handle outside said casing connected to the contact arm within the casing, stop means to limit the movementor the control handle and contact arm, vthe stop'at one end permitting said'contact arm to move beyond the transformer winding, and a slab of material disposed Vatsaid end of' the ltransformer winding to receiveandlguide the contact transformer winding. l

' 2 1. A variable-voltage step-downtransformer arm during its continued movement beyond the 5. for operatingv electrical toys, especially toy rail'- roads, from a household power line, said transformer comprising a laminated H type iron core' including center and outsidelegsjoined by transverse end legs, a primary winding consisting of a' ,5

number of layers of wire wound about said center f leg, a flexible cord and plug joined thereto for connection to a power line, a secondary winding A including a layer of closely wound Wire about the outside of the primary winding, a contact "arm oscillatable about an axis disposed transversely of the core legs and offset sidewardly from the center toward an outside leg, the length and pivoting of the contact arm being so related to the transformer winding that the end of the contact arm may be swept entirely across one side face of the 'winding in order to vary the voltage in a smooth` continuous manner, a casing surrounding said transformer andsaid contact., arm, a control handle outside said casing connected to the contact arm within the casing, stop means to limit the movement of the control handle and contact arm, the stop at one end permitting said contact arm to move beyond the transformer winding to open-circuit the secondary circuit, and a slab of insulation material disposed at said end of the transformer winding to receive and guide the contact arm during its continued movement be,- A yond the transformer Winding.

22. A', variable voltage step-down transformer for operating electrical toys, especially toy rail-.- roads, from a household power line, said transformer comprising a laminated H type iron core including center and outside legs joined by transverse end legs, a primary winding consistingl of 'a number of layers of wire woundl ,.about said so arranged that theend of the contactarm.

may be swept entirely across the outer layer of secondary Winding to vary the voltage in a smooth continuous manner from about half to maximum value, stops to limit the movement of the con'- tact arm, the stop at the low voltage-'end permitting the contact arm to move beyond` the winding. l Y

23'. A variable voltage step-down transi'ormer for operating electricaltoys, especiallytoy railroads, from a household powerline', said trans. former comprising a laminated H type iron-core with a center leg rectangular in cross-section, a primary winding consisting of -a number of layers of wire Wound about said. vcenter leg, fa iiexible cord and plug joined theretoifor connection to a. power line, a 'secondary winding including a layer oi."closely wound wire'about the outside ofthe primary winding', acontact arm 60 ing thatthe end of the contact arm may be swept 65" entirely across one of the iiat side' faces of the winding to vary the'output voltage in a'smooth continuous manner, a casing surrounding said transformer and said contact arm, means on the exposed part of saidI core for positioning the'70 same in spaced relation withrespect to the walls of the casing, a pair oi binding posts or con-- nections, one of which isconnected to one end 'of the secondary winding and the other of which is connected/to -saidmovabie contact arm, and

' and pivoting :of the contact arm being so related Ca. control handle 'outside said casing connected to the contact arm withinpthe casing, said co trol handle being insulated from said v'contact 24.=A variable voltage step-down ltransformer for operating electrical toys, especially toy rai1` roads, from a household power line, said transformer comprising a laminated H type iron core, a primary winding consisting of a number of layers of wire wound about the center leg of the core and adapted' to be' connected to a flexible lcord and plug for connection to a power line, a

secondary 4winding including rst and second layers of closely .wound wireabout the' outside of the primary winding, a contact arm oscillatablev about a pivot disposed transversely of the core legs and, oifset from the center leg, the length to the transformer winding that the.. movable end `the other of which is connected to said movable contact arm, a control handle outside said casing connected to the contact arm within the casing,'stop means to limit the movement of-the control handle and contact arm, the stop at the low voltage end permitting said contact arm to i move beyond the transformer winding, and a slab of material disposed at said end of the transformer winding to receive and guide the contact arm during its continued movement beyond the transformer winding. 

